Network analyzers for measuring the transmission and reflection parameters of any object under test disposed between two test ports must be calibrated with the help of so-called calibration standards in order to correct for system errors (see for example U.S. Pat. No. 4,982,164). Special methods or computation are used to obtain from the measured values resulting from said calibration measurements correction values or error characteristics which are subsequently taken into consideration for the actual object testing.
All of the conventional calibrating methods exhibit the common drawback that during the calibrating process the individual calibration standards are successively turned on and off, i.e. that they must be contacted afresh. This multiple change of calibration standards is especially troublesome when soldered or bonding connections between the test ports and the standards have to be broken and then made again. The use of the known calibrating methods is particularly disadvantageous also with those network analyzers in which antennas are connected to the test ports for radiating electromagnetic waves and in which in the free-space between the mutually spaced antennas the testing of objects such as humidity measurements are to be carried out on test objects disposed in the electromagnetic field between the antennas. The latter kind of network analyzers can be calibrated in accordance with known calibrating methods only by disposing the antennas successively at different mutual spacings and by accurately measuring said spacings, which cannot be done with high precision in the EHF-range.